Without limiting the scope of the invention, its background is described in connection with the identification of novel anti-microbial agents isolated from Aloe vera, as an example.
Heretofore, in this field, organisms that cause infectious disease, namely, viruses, bacteria, fungi and multicellular parasites, humankind has sought to control their morbidity and mortality. With the isolation and characterization of powerful antibiotics, beginning over half a century ago, the balance of power between humans and microbes has been shifted toward humankind. For several decades after the introduction of penicillin in the 1940's, for example, the conquest of infectious disease appeared imminent. The widespread use of antibiotics, added to the evolutionary flexibility of microbes, has made that victory less than certain.
An increasing number of bacteria, fungi and other microbes are developing resistance to antibiotics. A number of factors have contributed to the increase in microbes that are resistant to antimicrobial agents. The use of combinations of anti-microbial agents to treat nosocomial infections, particularly among patients whose immune systems are compromised by AIDS, chemotherapy, or immunosuppressive drugs, has led to a dramatic increase in multiple drug resistant (MDR) infections. Unfortunately, the future does not look bright in the war against infectious disease, as MDR strains of microbes continue to proceeding at an alarming rate. In fact, MDR strains are adapting faster than the introduction of new, more potent antibiotics.
Microbes have been developing strategies to cope with change for hundreds of millions of generations. In fact, some bacteria have generation cycles of 20 minutes, with each cycle providing the opportunity to evolve and adapt. Bacteria have adapted to an extraordinary range of conditions and developed defenses against all sorts of environmental threats, environmental and artificial. To a microbe the human body is just another environment to colonize. While antibiotics are just another toxic environmental agent against which the microbe must develop an escape strategy. For organisms with populations that have already adapted to such extreme environments as boiling underwater hot-springs, learning to cope and evade antibiotics was only a matter of time and evolution.
Overuse of antibiotics has contributed to the problem of MDR microbial strains. The indiscriminate use of antibiotics throughout the world contributes to the continued emergence of MDR strains of bacteria such as Pseudomonas, Streptococcus and Staphylococcus. MDR strains have evolved in large part because many patients fail to complete the required course of antibiotic treatment, allowing stronger members of the microbial pool to be selected for in the next round of treatment. Increases in ear and sinus infections in children have been caused by the use of antibiotics to treat viral infections, infections that are not susceptible to antibiotic treatment. The current trend in medicine is to prescribe second-line and even last-resort antibiotics in place of first-line antibiotics. Even when there is no reason to suspect resistance to first-line antibiotics, the drive toward using stronger, faster drugs is inevitable when faced with a sick patient. In the case of recurrent lung infections in cystic fibrosis patients, physicians have had no choice but to escalate to antibiotic treatment with second-line antibiotics, eventually causing the infecting bacteria to become resistant to all available antibiotics.
The emergence of MDR microbes has changed the balance between host and parasite, from a position in which the medical community seemed poised to achieve a conquest has lost ground in achieving a permanent conquest of microbial infection. But much has been learned in the process. Using a deeper understanding of microbes and their mechanisms of resistance, the biomedical community can continue to mount a broad array of defenses against them. The microbes growing resistance to traditional antibiotics has renewed the attention to medical basics, such as public health measures, that include a renewed effort to stem infectious diseases by increasing hygiene. For example, in HIV-infected populations, which have become breeding grounds for resistant microbes, renewed educational outreach efforts focus on the use of prophylactics.
Nosocomial infections present the greatest threat to immuno-compromised patients, because MDR microbes infect the most vulnerable patients. It is the increase in MDR of microbes, and in particular bacteria, that has led to a resurgence of interest in revitalizing and improving basic techniques (like hand-washing) for preventing the spread of infection. It has also increased the need for alternative, next-generation, anti-microbial agents. These anti-microbial agents, viz., anti-viral, anti-bacterial, anti-fungal and anti-parasitic, must also be safe for use in humans and other animals.
Antimicrobial-drug resistance is an increasingly important factor and poses a serious international challenge to public health in community and institutional settings. The list of resistant bacteria of major public health importance includes those causing tuberculosis, gonorrhea, pneumococcal infections, and hospital-acquired enterococcal and staphylococcal infections. Antimicrobial-drug resistance has resulted in prolonged and more serious illness, the use of more expensive and often more toxic drugs and drug combinations, and increased fatality rates.
While pharmaceutical and biotechnology companies are constantly developing novel products based on presently known antibiotics to overcome resistance, the next-generation of anti-microbial agents must break from the known approaches to isolate and characterize these activities. A better understanding of the microbiology and molecular genetics of microbial resistance is leading to the development of a new generation of anti-microbial agents that use an approach that is intended to attack standard mechanisms of action to kill bacteria or fungi. These so called new approaches to fighting microbial infections rely on variations of existing drugs having longer half-lives and more potent effects, but rely on the existing database of pharmaceutics to attempt to outpace the microbes ability to evolve.